Devices for supporting and adjusting a form cylinder in a printing group of a rotary printing press

ABSTRACT

A forme cylinder is supported and adjusted in a printing group of a rotary printing press, which group includes a transfer cylinder and a counter-pressure cylinder, which two cylinders include interacting support elements. The forme cylinder does not include a support element which interacts with the transfer cylinder. The forme cylinder has a shaft distance that can be adjusted during printing to adjust a contact pressure between the forme cylinder and the transfer cylinder. The forme cylinder may be covered with a waterless printing forme. The contact pressure between the forme cylinder and the transfer cylinder can be adjusted to a property, such as the compressibility, of the waterless printing forme.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. utility patent application is the U.S. national phase, under35 USC 371, of PCT/DE2003/000270, filed Jan. 31, 2003; published as WO2004/000557 A1 on Dec. 31, 2003 and claiming priority to DE 102 28 242filed Jun. 25, 2002, the disclosures of which are expressly incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention is directed to devices in a printing group of arotary printing press, having a forme cylinder, a transfer cylinder anda counter-pressure cylinder. A support element cooperating with thetransfer cylinder is not provided at the forme cylinder. The formecylinder can have a waterless printing forme.

BACKGROUND OF THE INVENTION

A device in a printing group of a rotary printing press, having a formecylinder, a transfer cylinder and a counter-pressure cylinder is knownfrom WO 00/41887 A1. The transfer cylinder and the counter-pressurecylinder have cooperating support elements. To compensate for unwindingdifferences between the cylinders with the support elements, and/or toprevent unacceptable wear of the support elements, it has beenoptionally provided that a normal force, i.e. a contact force, betweenthe support elements can be adjusted, and that a shaft distance betweenthe transfer cylinder and the counter-pressure cylinder can be changed.One of the two cylinders with support elements is seated in an eccentricbushing.

Cylinders of a rotary printing press and having so-called bearer rings,are known from DE 29 26 570 C2 and from DE 195 01 243 A1. The bearerrings of adjoining cylinders are supported on each other. Bearer ringsare support elements, configured as barrel rings, and arranged on thejournals of cylinders and supporting the two ends of the cylinder inorder to reduce undesired cylinder vibrations and in this way to makepossible clean printing in spite of groove beat. The bearer rings are ofsuch dimensions that the bearer rings arranged on cooperating adjoiningcylinders roll off on each other. Thus a defined shaft distance betweentwo printing group cylinders of a rotary printing group is also achievedby the use of such a bearer ring arrangement. Because of their supportof the cylinders, which bearer ring support exists in addition to theseating of the cylinders, the bearer rings cause dampening of cylindervibrations, which are excited, in the course of the rotation of thecylinders, by grooves, which grooves have necessarily been cut into, orformed in the cylinders for holding dressings.

As can be seen in DE 28 02 153 A1, the bearer rings are pushed togetherunder considerable pressure. This is done in order to prevent the bearerrings, which run off on each other, from lifting or sliding off duringthe printing process.

An arrangement for setting the contact pressure between cylinders of arotary printing press is known from DD-PS 113 187. The arrangement forplate cylinder adjustment is constructed analogously to that forprinting cylinder adjustment.

Document DE 41 42 791 A1 relates to a device for setting the printingpressure, as well as for setting the print-on and print-off setting ofprinting presses, which can be selectively operated with bearer ring orwithout bearer ring contact. The device makes possible a common,synchronous adjustment of several cylinders with respect to each other,in a single adjustment process while printing with the bearer rings incontact, as well as with the bearer rings out of contact. In particular,with a change of the printing pressure between the rubber blanketcylinder and the printing cylinder, the plate cylinder is moved tofollow the rubber blanket cylinder in such a way that, independently ofthe printing gap between the rubber blanket and the printing cylinders,the shaft distance between the plate cylinder and the rubber blanketcylinder always remains the same.

SUMMARY OF THE INVENTION

The object of the present invention is directed to providing a devicewith a forme cylinder, a transfer cylinder and a counter-pressurecylinder in a printing group of a rotary printing press.

In accordance with the present invention, this object is attained by theprovision of a printing group of a rotary printing press and having aforme cylinder, a transfer cylinder and a counter-pressure cylinder. Thetransfer cylinder and the counter-pressure cylinders have cooperatingsupport elements. A support element cooperating with the transfercylinder is not provided at the forme cylinder. A shaft distance betweenthe forme cylinder and the transfer cylinder can be adjusted to set acontact pressure. The forme cylinder may carry a waterless printingforme. The contact pressure between the forme cylinder and the blanketcylinder can be matched to a property of the printing forme.

The advantages to be gained by the present invention reside, inparticular, in that, in the course of setting and adjustment of thecontact pressure required between the forme cylinder and the transfercylinder, support elements between these cylinders, which supportelements correspond with each other and which limit the adjusting path,need not be taken into consideration. Since support elements customaryin printing groups, such support elements being, for example, in theform of bearer rings, are mostly put into contact under prestress, aconsiderably reduced force is required for setting and adjustment ifthese support elements are omitted at the forme cylinder. Thus,appropriate drive mechanisms and force transfer devices can beconfigured with lower output, which leads to savings of cost and energy.Setting the contact pressure between the form cylinder and the transfercylinder is therefore made easier if no support elements exist at theforme cylinder. On the other hand, the support elements remain in thoselocations where they are needed, for example in such locations asbetween the transfer cylinder and the counter-pressure cylinder. Supportelements are required at this location, because clamping grooves formedin the transfer cylinder are the main cause of the so-called groovebeat. The transfer cylinder should therefore remain supported in orderto increase its quiet running. The configuration of a printing group inaccordance with the present invention has particular advantages in caseswhere the forme cylinder is covered by a printing form that is coatedwith silicon. The durability of the printing forme applied to a formecylinder is increased because of the improved adaptability of thecontact pressure between the forme cylinder and the transfer cylinder,which increased durability applies, in particular, to waterless offsetprinting. Because of the provided capability of adjustment of thecontact pressure, the print quality which can be achieved by the use ofthe printing forme can be, in addition, improved even during the ongoingprinting process. Moreover, lubrication and cleaning of the bearer ringsarranged between the forme cylinder and the transfer cylinder, whichwould otherwise be required, is not required because those bearer ringshave been omitted.

BRIEF DESCRIPTION OF THE DRAWING

The sole drawing FIGURE is a simplified representation of a printinggroup with a forme cylinder, a transfer cylinder and a counter-pressurecylinder in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A planographic printing process, in particular a printing groupoperating by waterless offset printing, is depicted in the sole drawingFIGURE as an example of a printing group with which the presentinvention may be used. A print position of a rotary printing press, thatis arranged in the printing group, is formed by a cylinder 01 which, forexample, is embodied as a counter-pressure cylinder 01, and anothercylinder 02 which, for example, is embodied as a transfer cylinder 02. Amaterial to be imprinted, for example a paper web which is notspecifically represented, is conducted between these two cylinders 01,02. These cylinders 01, 02 are provided, at both ends of theirrespective barrels 03, 04, with support elements 06, 07, respectivelywhich may be, for example, bearer rings 06, 07, wherein each cylinderbarrel 03, 04 has a length L. The bearer rings 06,07 of the adjoiningcylinders 01, 02, respectively, roll off in pairs against each other.The cylinders 01, 02 are provided with journals 08, 09, respectively,which journals are seated by bearings 11, 12 in lateral frames 13, 14. Afirst shaft distance a1, for example of a1=400 mm, between the rotaryshafts 16, 17 of the two cylinders 01, 02 and extending beyond the shaftjournals 08, 09, respectively can be changed because, for example, atleast one cylinder 01 or 02 of the cooperating pair of cylinders 01, 02is arranged to be pivotable or to be displaceable. At least one formecylinder 21, that is provided with a rotary shaft 22, which is alsoseated in the lateral frames 13, 14, preferably in eccentric bushings18, 19, is assigned to the transfer cylinder 02. The rotary shaft 22 ofthe forme cylinder 21 and the rotary shaft 17 of the transfer cylinder02 have a second shaft distance a2 with respect to each other, whichsecond shaft distance a2 can be set and, if required, can also beadjusted as needed.

On its surface area 23, the forme cylinder 21 can have, for example,four printing formes 26 to 29. The printing formes 26 to 29 can beconfigured as printing plates, for example, and in particular aswaterless planographic printing formes, which printing formes are placedonto the forme cylinder surface area 23 and are maintained in grooves 24that have been cut into the forme cylinder 21. The covering of the formecylinder 21 can, for example, be such that respectively two printingformes 26 and 27, or 28 and 29, with the latter printing forme 29 beingnot specifically represented in the sole drawing, since in thisrepresentation it is located on the back of the forme cylinder 21, arearranged next to each other in the circumferential direction. Theside-by-side arranged printing formes 26 and 27, or 28 and 29, are eachoffset with respect to the other by 90°. On its surface area 31, thetransfer cylinder 02 has one or several printing blankets 32, which arealso preferably maintained in one or in several grooves 24 which havebeen cut into the surface area 31 and which are, if required, arrangedoffset with respect to each other in the circumference of the transfercylinder 02.

The described printing location can also be arranged, for example, in afour-cylinder printing group, in which the counter-pressure cylinder isalso configured as a transfer cylinder. In such an arrangement, afurther, non-represented form cylinder is assigned to this transfercylinder in such a way that these two cylinders run off on each other.This printing group can also be expanded into an eight-part tower.However, it is also possible to employ the previously described printinglocations in connection with a counter-pressure cylinder in afive-cylinder printing group, for example, in a ten-cylinder printinggroup consisting of two five-cylinder printing groups, or in anine-cylinder printing group.

The printing group being described here is typically operated in aplanographic printing process and preferably uses a printing forme thatis suitable for waterless offset printing, commonly referred to as “dryoffset printing”. The expression “waterless offset printing” identifiesa printing group operating without a dampening system. No supply of adampening agent, for forming the non-printing areas, is required inaddition to the supply of printing ink. With waterless offset printing,the application of a film of moisture to the printing forme is omitted,which film of moisture, in so-called “wet offset printing”, prevents thenon-printing portions on the printing forme from picking up printingink. In waterless offset printing this prevention of ink pick up in thenon-printing areas of the printing forme is achieved by the use ofspecial printing inks and by a special structure of the surface of theprinting forme.

A printing forme, that is suitable for use in waterless offset printing,preferably has a support layer, or a substrate, which can be made ofaluminum and which can have a suitable support layer or substratethickness for achieving the desired mechanical properties. Anink-accepting layer is applied to this support layer or substrate, aswell as an ink-rejecting layer that is applied above the ink acceptinglayer. The ink-accepting layer can be embodied as a polyethylene film.Its thickness can lie in the range between 5 and 50 μm, and itpreferably is approximately 20 μm. The ink-rejecting layer can consist,for example, of silicon. Its thickness is suitably selected. It can liewithin the range of a few μm, for example with a thickness ofapproximately 2 μm. In waterless offset printing, the ink-rejectingsilicon layer takes over the role of the hydrophilic layer used in wetoffset printing, which hydrophilic layer can be covered by a dampeningagent and prevents that area of the printing forme from picking up ink.An adhesive or a base layer can lie between the substrate and theink-accepting layer in the form of, for example, a titanium oxide layer.In U.S. Pat. No. 5,487,338, a printing form that is suitable forwaterless offset printing and which is a product of the Presstekcompany, and sold under the name PearlDry is described by way ofexample.

In waterless offset printing, a problem sometimes occurs because, due tothe lack of dampening agent, an increased temperature can possibly occurin the printing group, which increased temperature is too high for theprinting process, or for the printing inks used. It has accordingly beenproposed, in EP 652 104 A1, to control the temperature of the surface ofcylinders used in a printing group for waterless offset printing.Moreover, in a printing group operating without a dampening agent,soiling resulting from dust and from particles rubbed-off the materialto be imprinted, as well as from ink residue, can be very problematic,because cleaning of the cylinders, which would otherwise be performed bythe dampening agent, no longer exists. Accordingly, with the use of toostrong a contact pressure between the forme cylinder and the transfercylinder, wherein the force forming the contact pressure can beapproximately 10 N per cm of barrel length, the danger of grindingexists. For these reasons, and in view of the rather reduced mechanicalstrength and the reduced temperature resistance of the printing formesfor waterless offset printing, in comparison with conventional printingformes, which are typically essentially completely made of an aluminumalloy, it is necessary to configure the printing group used in waterlessprinting in such a way that the contact pressure between the formecylinder and the transfer cylinder can be changed in accordance with theproperties of a waterless printing form and thus can be adapted asneeded. In this case, the adaptability takes place, in particular, withrespect to the property of pressure stressing of the printing forme. Itcan also be related to the temperature stressing or to surface hardness,and in particular to scratch resistance, and therefore to the wearresistance of the printing forme. Furthermore, the frictional heat,which is caused by the contact pressure, has an effect on the behaviorof the printing ink used in the printing process, in particularaffecting the ink's flowability and its adhesion to the printing forme,and finally on the material to be imprinted, and therefore the printquality, so that the setting and adjustment of the contact pressure canalso take place by taking these process parameters into consideration.Furthermore, with some applications it can also be useful to control thetemperature of the form cylinder 21 in addition to the described steps.A temperature-control medium can flow through at least one coolingconduit, and preferably can flow through several such cooling conduits,which are arranged in the forme cylinder 21. At least one such coolingconduit is preferably arranged closely underneath the surface area 23 ofthe forme cylinder 21.

The contact pressure between the forme cylinder 21 and the transfercylinder 02 can be set or changed by variance of the second shaftdistance a2 between the forme cylinder 21 and the transfer cylinder 02.The shaft distance a2 has different values at different contactpressures. During the printing process, the forme cylinder 21 can be indifferent positions in relation to the transfer cylinder 02. Thisvariance or adaptation can be easily performed if the forme cylinder 21does not have a support element, such as a bearer ring 06, 07,cooperating with the transfer cylinder 02. Such a support element 06,07, if it were arranged on the forme cylinder 21, would limit theadjustment possibilities of the forme cylinder 21, or would at leastmake them considerably more difficult. At the same time support elements06, 07, such as, for example, support elements in the form of bearerrings 06, 07, have been arranged between the transfer cylinder 02 andthe assigned counter-pressure cylinder 01, in particular for improvingthe quiet running of the transfer cylinder 02. A contact pressurebetween the forme cylinder 21 and the transfer cylinder 02 can also beset, preferably during an ongoing printing process. This can be done, inparticular, by remote control from a command console which is assignedto the printing press, by the step of a change of their shaft distancea2, and can be adjusted with regard to a contact pressure which isoptimal with respect to the durability of the printing formes 26 to 29and to the print quality desired.

It is advantageous that the rotary shaft 22 of the forme cylinder 21 isin operative connection with at least one eccentric bushing 18, 19, witha lever arrangement, or with a linear drive mechanism, both of which arenot specifically depicted and by use of which the forme cylinder 21 canbe placed against the transfer cylinder 02 in a desired or required way.An eccentric cylinder bearing, without bushings, can be used in place ofthe eccentric bushing 18, 19. In a printing group configured inaccordance with the present invention, the support element 07 of thetransfer cylinder 02 and the support element 06 of the counter-pressurecylinder 01 are preferably still arranged so that they roll off on eachother. It is of advantage that the transfer cylinder 02 and thecounter-pressure cylinder 01 can be distanced from each other, forexample by pivoting or by traveling a displacement path. Thus, asindicated in the sole drawing FIGURE by the directional arrows 33 and bythe seam 34 in the lateral frames 13, 14, the portion of the lateralframes 13, 14 in which the counter-pressure cylinder 01 is seated can beconfigured to be movable with respect to the remaining parts thereof,for example for conducting a web of a material to be imprinted, such as,for example, a paper web, between the counter-pressure cylinder 01 andthe transfer cylinder 02. In this way, the setting of the first shaftdistance a1, and therefore the setting of the contact pressure betweenthe counter-pressure cylinder 01 and the transfer cylinder 02, isindependent of the setting of the shaft distance a2 and therefore isalso independent of the corresponding contact pressure between thetransfer cylinder 02 and the forme cylinder 21. As previously mentioned,the counter-pressure cylinder 21 can also be configured as a transfercylinder and can form a further printing location together with afurther forme cylinder.

While a preferred embodiment of devices for supporting and adjusting aforme cylinder in a printing group of a rotary printing press, inaccordance with the present invention, has been set forth fully andcompletely hereinabove, it will be apparent to one of skill in the artthat changes in, for example the overall sizes of the printingcylinders, the drives for the cylinders, and the like could be madewithout departing from the true spirit and scope of the presentinvention which is accordingly to be limited only by the amended claims.

1. A printing group of a rotary printing press comprising: a formecylinder; a transfer cylinder in contact with said forme cylinder; afirst support element on said transfer cylinder; a counter-pressurecylinder in contact with said transfer cylinder; a second supportelement on said counter-pressure cylinder and engagable with said firstsupport element, said first and second support elements on said transfercylinder and on said counter-pressure cylinder cooperating with eachother to set a first contact pressure between said transfer cylinder andsaid counter-pressure cylinder; a shaft distance between said formecylinder and said transfer cylinder; and means for adjusting said shaftdistance during an ongoing printing operation of said printing group toset a second contact pressure between said forme cylinder and saidtransfer cylinder.
 2. The printing group of claim 1 wherein a positionof said forme cylinder with respect to said transfer cylinder can beset.
 3. The printing group of claim 1 wherein said shaft distance hasdifferent values to vary said second contact pressure.
 4. The printinggroup of claim 1 further including at least one printing forme coatedwith silicon on said forme cylinder.
 5. The printing group of claim 1further including at least one waterless printing forme on said formecylinder.
 6. The printing group of claim 1 where said forme cylinder hasa surface and further including a printing plate securable to said formecylinder surface.
 7. The printing group of claim 1 wherein said meansfor adjusting said shaft distance is an eccentric bearing.
 8. Theprinting group of claim 7 wherein said eccentric bearing is an eccentricbushing.
 9. The printing group of claim 1 wherein said support elementsroll off against each other.
 10. The printing group of claim 1 furtherincluding a second forme cylinder and wherein said counter-pressurecylinder is a second transfer cylinder cooperating with said secondforme cylinder.
 11. The printing group of claim 1 further including adisplacement path defining a path of movement of said transfer cylinderand said counter-pressure cylinder.
 12. The printing group of claim 1wherein said printing group is a component of a four cylinder printinggroup.
 13. The printing group of claim 1 wherein said forme cylinder istemperature regulated.
 14. The printing group of claim 13 furtherincluding at least one cooling conduit in said forme cylinder and meansflowing a temperature regulating medium through said at least onecooling conduit.
 15. The printing group of claim 14 wherein said atleast one cooling conduit is arranged close to a surface area of saidforme cylinder.